Ariel

Due to the recent evidence of the Ito wild streetport eating sideseals left and right, I have become worried that my end irons have become scrap metal. I have ported my 4 port secondaries about 1-2mm outside of the track made by the leading edge of the sideseal. This track can be seen as the dotted line to the left on my template, and my port shape is the thin red line :



As this is for a NA car, I was originally going to use a set of s5 9.7:1 rotors, but now that it seems like my sideseals might be compromised by the porting, I was contemplating solutions. One thing I thought of was that rx8 rotors seem to have the sideseal placed further out, and therefore I could perhaps get some machined to 2mm apex seals and use those instead?

Pictures of the two kinds of rotors :



Anyone with rx8-rotors experience care to comment?



Alex

R.P.M.

Sorry I dont have experiance with this sort of thing, but its something I've wanted to try for a while now



I think it should work, intrested in hearing what others say.

ChainSawOnSteroids

I need to know this too!!! Im using rx8 eshaft and stat gears, can i use the rx8 rotors???

ChainSawOnSteroids

ALSO, could the apex, side, and corner seals from the fc be used in a rx8 rotor?

I found out that the rotors can be used in older motors, the only thing is Im not certain about side seals, they come in different lengths, but can i reuse my old side seals?

ChainSawOnSteroids

Heres another thing, the apex seals in the 8 are shorter and cannot withstand the pressure going over the exhaust port, so you would have to have the rotors machined to accept the older apex seals. If using the 8 eshaft you have to balance the rotating assembly since the shaft is lighter.

heretic

I've never built an engine with an extreme early opening side port before.



Ito says you have to use the Hurley side seals. My question is, is the side seal failure problem only a problem with .8mm side seals? Hurley does not make 1mm side seals such as you would need for '74-85 rotors.

PDF

Yes you can machine to rx8 rotors to take std 2mm or 3mm apex seals. Longer cut-them-yourself side seals are available from mazda and recommended for pre renesis engines. Don't use the combustion ring outside the oil seals its not needed. Use the rx8 stat gears, just make sure you oval the rear gear oil feed hole to line up with the hole in the earlier iron. Don't use the rx8 crank, the main bearing oil galleries don't line up when using earlier irons. Use an rx8 rear counterweight and conventional front weight when you get the rotating assm balanced.

Ariel

PDF, you seem to have experience with the rx8 rotors, can you confirm that the sideseals are indeed placed further out like the pictures suggests?



It seems to me that regardless of whether I can save my end-irons by using rx8-rotors - if the sideseals are placed further out, you will always be able to make a bigger streetport (perhaps not quite as big as mine) and achieve higher power than by using the S5 rotors. So even though the general consensus is that there is no gain in power from the 0.3 step in compression, for streetport motors you should be able to achieve a gain if you port accordingly. Not to mention the gain you should get from the factory bevel on the rotors.



I remember reading about someone doing a back to back comparison between renesis and s5 rotors with almost zero gain, but I think that was for a racecar with peripheral port. For a streetport gains might still be possible.





Alex

Kim

Ha, godt set Alex.



I never even gave that a thought before now.

Now how do we figure out when the ports(non 6port) open with the beveled 8'Rotors? Someone know this.?

PDF

Correct on all counts. Just be aware the rx8 side seals are a different shape to earlier ones, looking at them end on they have a taper down one side. All this means is you can't use the earlier side seals.